Piston



F. JARDINE Dec. 9, 1930..

PISTON Filed April 9, 1925 INVENTOR,

TTORNEYS Patented Dec. 9, 1930 UNITED STATES PATENT OFFICE FRANKJABDINE, OF CLEVELAND, OHIO, ASSIGNOB, BY MESNE ASSIGNMENTS, TO THEOLEVEI'AND TRUST COMPANY, 01' CLEVELAND, OHIO, A CORPORATION 01' OHIOPISTON Application filed April 9, 1928. Serial No. 100,771.

This invention relates to pistons and more particularly to pistonscomposed of a material having a higher or difl'erent co-efiicient ofexpansion than that of the cylinders in which they are to operate, asfor instance, where aluminum or aluminum alloy pistons are used incylinders of cast iron or the like.

As is well known, such pistons possess many desirable qualities such aslightness,

high heat conductivity and the like. However, the difl'erences inexpansion of the pistons and cylinders produce various difliculties anddisadvantages, for example, the pistons will either stick when hot orwill slap when cold.

The principal object of my invention is to provide a piston which may bemade of aluminum, aluminum alloy, or the like, which can be fitted witha very small clearance and which will maintain this clearancesubstantially unchanged throughout the temperature ranges met inpractice, without slapping, binding, scoring of the cylinder, or unduewear in the piston itself.

These and other objects of my invention, as well as the inventionitself, will be better understood from the description of one practicalembodiment of the invention which is illustrated in the accompanyingdrawings, in 0 which- Fig. 1 is a side elevation of a piston embodyingthis invention;

Fig. 2 is a central longitudinal section taken on line 2-2 of Fig. 1;

s5 Fig. 3 is a bottom plan view; and

Fig. 4 is a central longitudinal section at right angles to that of Fig.2.

The piston shown has a head 1 and a skirt 2, separated part way of theircircnmference by an air gap 3 and integrally Joined for the remainder asat 4.

The head is preferably cup-shaped and is shown as having a top 5 and adepending, annular flange 6 which may be provided with circumferentialgrooves 7 for the piston rings.

The skirt is provided with thrust faces intermediate the openings 19 and20 through the skirt and in alignment with the opening through the wristpin hearing. The skirt thrust face 17 which bears the load on theexpansion stroke is integral with the head as shown at 4. In theembodiment shown the groove 3 extends for about two hundred and seventydegrees about the piston.

Dependin from the center of the top is a column 8 w ich carries a wristpin bearing or boss 9. Webs 10, 11, 12 and 13 radiate from the centralcolumn and are integrally joined to the top and flange of the head andto the wrist pin hearing. The bearing member 9 is also connected to theskirt in the embodiment shown by web 12 which is extended downwardly andoutwardly to the skirt and integrally joined thereto from the memg5 ber4 to the bottom of the skirt, thus materially strengthening andstiffening the connection as well as the head and skirt separately. Theportion of the piston which bears the thrust loadis thus greatlystrengthened to bear the explosion load. In the embodiment shown, theweb 12 is substantially rectangular from the top to the lower part ofthe boss, filling in the space between and joining the top of the head,the inside wall of the side of the head, the cross webs 11 and 13 andthe inside wall of the thrust face 17 of the skirt. Below the boss, theweb 12 is tapered ofi until it is triangular in shape. The web 10 islikewise rectangular in shape to the lower edge of the side wall of thehead; from there it tapers to the boss to which it is joined at aboutthe center. The webs are thus constructed to take the working strainsand so strengthen and brace the piston that there be no danger offlexing the head, top or otherwise distorting the top or the thrust face17 relative to each other or the bearing 9. This is all the moreimportant since the other portions of the piston must be made flexibleto allow for the difference in expansion between the aluminum piston andthe iron cylinder. In the embodiment shown this flexibilit isaccomplished by a slit 14 in the thrust ace 18. Preferably this slitextends the entire length of the skirt.

To limit the expansion and contraction of the skirt to, or substantiallyto, that of the cylinder in which it operates, I span this slit withmembers made of material having sub- 100 stantially the sameco-efiicient of ex ansion as the cylinder. In the embodiment s own Ihave employed bands 15 and 16 of iron since the cylinder in which thispiston is to be employed is iron. The bands are shown as rods and aremounted in ooves 23 and 24 in the inside of the skirt. he ring 15 isabove the boss and just below the slit 3. The ring 16 is just above thelower end of the piston. The rings are maintained in place by somesuitable means such as bearin s formed in the web 12 and ribs 25 and 26ormed on the inside of the piston wall.

Preferably the rings are placed in the mold in which the piston is castso that the skirt is cast around them. When the skirt shrinks oncooling, the shrinkage of the aluminum be ing greater than that of thesteel the rmgs are placed under com ression and the skirt under tension,thus ho ding the skirt tightly u n the rings under all serviceconditions. This it will be seen that the size of the skirt iscontrolled b the expansion of the rings. The split furnishes room forany circumferential expansion of the skirt.

I do not wish to be limited to the embodiment of my invention shown, orthe details thereof, since it will be a parent that many departures maybe made rom both this embodiment and its details, without departing fromthe spirit of the invention.

I claim:

1. A piston comprising a head, a central depending wrist pin boss and askirt connected to the head at one side and separated from the head atthe opposite side.

2. A piston having a skirt split throughout its entire hei ht on oneside and spaced from the head for the majority of its circumference andclosed one piece rings of a different material inside said skirtcontacting the same throughout their length and maintained undercompression thereby.

3. A piston having a head, a depending wrist pin boss carried thereby, acentral web perpendicular to the axis of the boss and connecting theboss to the head, and a split skirt connected to the head and to oneside of the web.

4. A piston having a head, a de nding wrist pin boss carried thereby, asp it skirt connected to the head at one side, a diametric web integralwith the head, boss and skirt, and rings within the skirt and exertingoutward ressure thereon.

5. piston having a head a skirt, a diametric web inte al with the headand skirt, the head and skirt being integrall connected in the vicinitof the we and a sp it th: iughout the heig t of the skirt and oppositethe junction of the skirt and web.

6. In a piston for an internal combustion engine, thecombination of ahead and a skirt portion, each made of a material of a relatively highco-efiicient of expansion under heat, the skirt being connected to thehead at one side only, the remainder of the skirt being separated fromthe head, said skirt being provided with an opening to permit expansionand contraction of the skirt and rings, of a material having a lowerco-e cient of expansion than the material of which the skirt is madeconnected to the skirt spanning said opening, and regulating theexpansion. and

contraction of the skirt.

In a piston for internal combustion engines, the combination of a head,a skirt and piston pin bearing all made of a material of a relativelyhigh co-eflicient of expansion, the skirt comprising thrust faces, oneof which only is connected to the head, the other thrust face beingprovided with an opening to permit the expansion and contigction of theskirt and means of a material of a lower c0- eflicient of expansion thanthe material of the skirt mounted in said skirt and regulating theexpansion and contraction of the skirt.

8. In a piston for internal combustion engines, the combination of ahead, a skirt and a wrist pin bearing made of a material of a relativelyhigh co-efiicient of expansion, the skirt comprising thrust faces, oneof which only is connected to the head, the other portion of the skirtbeing separated from the head by an air gap, the other thrust face beingprovided with an opening extending the length of the skirt permittingthe expansion and contraction of the skirt and rings of a lowerco-eflicient of expansion than the material of the skirt mounted in theskirt spanning said openings and regulating the expansion andcontraction of the skirt.

9. In a piston for an internal combustion engine, the combination of acup-shaped head, a skirt and a bearing for a wrist pin made of materialof a relatively high co-efiicient of expansion, said skirt comprisinthrust faces, a substantially triangular shap web extending from thelower portion of the head on one side of the piston to the lower portionof the skirt on the other and connecting the top and bottom portions ofthe inside of the head, the piston pin bearing and the inside of one ofthe thrust faces of the skirt, the thrust face of the skirt thusconnected to the web being also connected to the head, the otherportions of the skirt being separated from the head, the other thrustface bein split from end to end and rings of a materia of a differentco-efiicient of expansion than that of the skirt being mounted in saidskirt spanning said slit in the other thrust face and regulating theexpansion and contraction of the skirt. Y

10. In a piston for an internal combustion engine, the combination of acup-shaped head, a skirt and a wrist pin bearing, said skirt beingconnected to the head by a substantially triangular shaped web whichalso connects the boss to the skirt and web and which extends from thehead to the lower portion of one side of the inside of the skirt,uniting that portion of the skirt and the wrist pin bearing with the topand bottom of the inside of the head.

11. In a piston for an internal combustion engine, the combination of acup-shaped head, a skirt and a wrist pin bearing, said skirt beingconnected-to the head by a substantially triangular shaped web whichalso connects the boss to the skirt and web and which extends from thehead to the lower portion of one side of the inside of the skirt,uniting that portion of the skirt and the wrist pin bearing with the topand bottom of the inside of the head, and webs extending substantiallyperpendicular to said triangular-shaped web and joining the saidtriangular-shaped web to other portions of the top and side walls of thehead.

12. A piston comprising an integrally cast head and skirt, the skirtbeing split throughout its entire height on one side and separated fromthe piston head throughout the majority of its periphery and spacedclosed one piece rings of a different material inside the skirt, andmaintained under compression thereby.

13. A piston comprising an integrally connected head and skirt, theskirt being longitudinally split and two closed rings of a differentmaterial inside the skirt and maintained under compression thereby, onecontrolling the expansion of the skirt above the wrist pin and the othercontrolling the expansion of the skirt below the Wrist pin.

In testimony whereof I hereunto afiix my signature this 5 day of April,1926.

FRANK JARDINE.

